CN113400300B - Servo system for robot tail end and control method thereof - Google Patents
Servo system for robot tail end and control method thereof Download PDFInfo
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- CN113400300B CN113400300B CN202110562573.3A CN202110562573A CN113400300B CN 113400300 B CN113400300 B CN 113400300B CN 202110562573 A CN202110562573 A CN 202110562573A CN 113400300 B CN113400300 B CN 113400300B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1602—Programme controls characterised by the control system, structure, architecture
- B25J9/161—Hardware, e.g. neural networks, fuzzy logic, interfaces, processor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J13/00—Controls for manipulators
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1628—Programme controls characterised by the control loop
- B25J9/1653—Programme controls characterised by the control loop parameters identification, estimation, stiffness, accuracy, error analysis
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1656—Programme controls characterised by programming, planning systems for manipulators
- B25J9/1664—Programme controls characterised by programming, planning systems for manipulators characterised by motion, path, trajectory planning
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1694—Programme controls characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion
- B25J9/1697—Vision controlled systems
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Abstract
Embodiments of the present invention provide a servo system installed at a robot tip and a control method thereof, in which a tip servo module coupled between a robot tip joint and a process tool transmits data collected by a laser sensor thereof to a tip servo controller; the end servo controller calculates track compensation parameters according to the data collected by the laser sensor, and generates and transmits corresponding servo control signals to servo motors in the end servo module according to the track compensation parameters so as to enable the corresponding process tool to move to a specified position at a specified speed. The robot tail end servo system can independently or auxiliarily accurately control the running track of the robot tail end executing mechanism, and can meet the requirements of high-speed or/and high-precision industrial application.
Description
Technical Field
The invention relates to the application field of industrial robots, in particular to accurate servo sensing control of an end effector of a robot in high-speed operation.
Background
The industrial robot is a multi-joint manipulator or a multi-degree-of-freedom machine device facing the industrial field, and can enable the end effector of the robot to move along a given track according to a certain speed and a certain gesture by linkage servo control and cooperation of all joints or degrees of freedom so as to complete a certain action. Depending on the application requirements, different end effectors may be mounted on the robot end joints, for example, process tools such as welding guns, grippers, suction cups, nozzles, etc. The process tool moves to another pose along a given track by linkage servo control of each joint of the robot, so that corresponding process machining or manufacturing processes are completed. In the manufacturing, processing and assembling processes in the field of high-precision tip manufacturing, the processing precision of products is critical, and high requirements are put on the absolute positioning precision and path precision of the tail end of the robot. At present, the industrial robot has high repeated positioning precision and low absolute positioning precision, which is limited by the mechanical structure of the robot and the servo precision of each joint. Particularly in high-end applications with high precision and high speed, it is difficult to achieve accurate trajectory tracking and control of the robotic end effector.
Disclosure of Invention
Therefore, an objective of the embodiments of the present invention is to provide a servo system installed at a robot end and a control method thereof, which can independently or auxiliarily and accurately control a moving track of an end actuator of the robot, so as to meet the requirements of the robot on high-speed and high-precision industrial application.
The above purpose is achieved by the following technical scheme:
According to a first aspect of embodiments of the present invention, there is provided a servo system for a robot tip, comprising a tip servo module coupleable to the robot tip and a tip servo controller communicatively coupled to the tip servo module, wherein: the tail end servo module comprises a first laser sensor, a communication module, a servo motor and a mechanical linkage mechanism thereof, wherein the tail end of the mechanical linkage mechanism is connected with a process tool for processing, and the tail end servo module sends data acquired by the first laser sensor to the tail end servo controller through the communication module and receives a control signal for the servo motor from the tail end servo controller; and the servo controller calculates a track compensation parameter according to the data acquired by the first laser sensor, and generates a control signal for the servo motor according to the track compensation parameter so as to indicate the servo motor to reach a specified position.
In some embodiments of the invention, the first laser sensor may be disposed at a location where the tip servo module is connected to a side of a process tool and is capable of capturing an image of the front of the travel of the robot tip.
In some embodiments of the present invention, the servo controller may detect a process track point to be processed according to data collected by the first laser sensor.
In some embodiments of the invention, the servo controller may further comprise a storage unit for storing the process trajectory points detected via the first laser sensor and for storing the calibration trajectory points of the predetermined robot end tool center point.
In some embodiments of the present invention, the end servo controller may determine a track compensation parameter by comparing a process track point detected during a process of the robot with the calibration track point, and generate a control signal to the servo motor according to the track compensation parameter.
In some embodiments of the present invention, the tip servo controller may predetermine a nominal trajectory point for a center point of the robotic tip tool with the tip servo at a null position by: before starting the technological processing procedure, starting the robot to execute a processing program corresponding to a teaching path of the robot for a plurality of times; in each running process, tracking and measuring the running track of the terminal servo module in real time, wherein the running track is represented by a series of position data of track points and corresponding time sequences; and fitting the measured multiple running tracks into a calibration running track of the tail end servo module, and simultaneously converting each track point on the calibration running track into a calibration track point of a corresponding tail end tool center point of the robot.
In some embodiments of the present invention, the tracking of the moving track of the measurement end servo module in real time may be performed by a laser tracker disposed in an external environment.
In some embodiments of the present invention, the end servo module may further comprise a second laser sensor disposed opposite the first laser sensor on a side of the end servo module to which the process tool is coupled.
According to a second aspect of embodiments of the present invention, there is provided a control method for a servo system according to the first aspect of embodiments of the present invention, in a robot processing engineering, acquiring an image of a front of a robot end traveling in real time by using a first laser sensor installed at an end servo module and transmitting to an end servo controller communicatively coupled with the end servo module; detecting a process track point to be processed based on an image acquired by a first laser sensor by the end servo controller; comparing the detected process track point with a predetermined calibration track point of a center point of a robot end tool by the end servo controller to determine track compensation parameters, and generating a control signal for a servo motor in an end servo module according to the track compensation parameters; and instructing, by the end servo module, the servo motor to reach a specified position based on a control signal from an end servo controller.
In some embodiments of the invention, it may further comprise predetermining a nominal trajectory point for a center point of the robotic end tool by: before starting the technological processing procedure, starting the robot to execute a processing program corresponding to a teaching path of the robot for a plurality of times; in each running process, tracking and measuring the running track of the terminal servo module in real time, wherein the running track is represented by position data of a series of track points; and fitting the measured multiple running tracks into a calibration running track of the tail end servo module, and simultaneously converting each track point on the calibration running track into a calibration track point of a corresponding tail end tool center point of the robot. In the above process, the end servo is at zero.
According to a third aspect of embodiments of the present invention, there is provided a computer readable storage medium having stored thereon a computer program which when executed implements the method according to the second aspect of the above embodiments.
The servo system and the control method for the tail end of the robot, which are provided by the embodiment of the invention, integrate sensing control, servo control and track planning, and can accurately track and correct the position of the tail end actuator of the robot in real time, thereby effectively improving the accuracy of the running track of the tail end actuator of the robot, and meeting the requirements of high-speed application or/and high-accuracy application, such as 3D printing, laser welding, spraying, gluing, high-accuracy compound motion (such as small circle cutting) and the like.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.
Drawings
Embodiments of the invention are further described below with reference to the accompanying drawings, in which:
Fig. 1 shows a schematic structure of a servo system for a robot tip according to an embodiment of the present invention.
FIG. 2 shows a simplified schematic diagram of an exterior side of an end servo module according to one embodiment of the invention.
Fig. 3 shows a working scenario intent of a servo system for a robot tip according to one embodiment of the present invention.
FIG. 4 shows a schematic diagram of a coordinate system involved in a servo system according to one embodiment of the present invention.
FIG. 5 illustrates a flow diagram of an online operation of a servo system according to one embodiment of the present invention.
FIG. 6 shows a schematic diagram of track following of a servo system according to one embodiment of the invention.
FIG. 7 shows a hardware architecture diagram of an end servo controller according to one embodiment of the invention.
Detailed Description
For the purpose of making the technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail by way of specific embodiments with reference to the accompanying drawings. It should be understood that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art without the inventive effort, are intended to be within the scope of the present invention, based on the embodiments herein.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, devices, steps, etc. In other instances, well-known methods, devices, implementations, or operations are not shown or described in detail to avoid obscuring aspects of the invention.
The block diagrams depicted in the figures are merely functional entities and do not necessarily correspond to physically separate entities. That is, the functional entities may be implemented in software, or in one or more hardware modules or integrated circuits, or in different networks and/or processor devices and/or microcontroller devices.
The flow diagrams depicted in the figures are exemplary only, and do not necessarily include all of the elements and operations/steps, nor must they be performed in the order described. For example, some operations/steps may be decomposed, and some operations/steps may be combined or partially combined, so that the order of actual execution may be changed according to actual situations.
In the high-end application fields of high precision and high speed, the robot tail end is often in a high-speed motion state, and the inertia is large, so that the robot tail end actuator is difficult to accurately track and control in real time. In one embodiment of the present invention, a servo system installed at a robot tip and a control method thereof are provided, which independently or auxiliarily accurately control a moving track of a robot tip actuator by performing track compensation on a robot tip TCP (Tool Center Point ) to meet the requirements of high-speed or/and high-precision industrial applications. Fig. 1 shows a schematic structure of a servo system for a robot tip according to an embodiment of the present invention. The robotic end servo system generally includes an end servo module and an end servo controller communicatively coupled to the end servo module. The end servo module can be mounted on the end joint of the robot or any tool. The end servo module may include a laser sensor, a communication module, and a servo motor and its mechanical linkage. The end of the mechanical linkage of the servo motor can be connected with a process tool required for corresponding process. The end servo module sends data collected by the laser sensor to the end servo controller via the communication module and receives control signals from the end servo controller to the servo motor. The servo motor can perform corresponding movements according to the received control signals to move the process tool to which it is connected to a designated position at a designated speed. When the robot is used for processing, the laser sensor in the tail end servo module is mainly used for detecting the actual processing track to be processed in advance, so that the tail end TCP of the robot can accurately track the processing track. Thus, the laser sensor, also called a front sensor, is arranged in front of the end servo module, and acquires front images in the direction of travel of the robot end in order to detect a number of process trajectory points to be travelled to based on these acquired images. In yet another embodiment, another laser sensor, similar to the front sensor, may also be mounted on the end servo module, all on the side of the end servo module that is connected to the process tool and located opposite the front sensor (and thus may also be referred to as a back sensor). Thus, when the tail end of the robot moves back and forth, one of the front sensor and the rear sensor is always used for collecting the front image of the running direction of the tail end of the robot so as to detect the technological track point to be processed in advance. That is to say, either of the two laser sensors mounted on the end servo module can be used as a front sensor, depending on the direction of movement of the robot end. When one of the laser sensors is used as a front sensor, the other is correspondingly a rear sensor, which in turn can capture images behind the robot tip, so that the captured images can be used for quality detection of the process. FIG. 2 illustrates a schematic diagram of the appearance of an example end servo module. As shown in fig. 2, the front and rear laser sensors are integrated with the end servo module, which is mounted on the side of the end servo module to which the process tool is attached. Each laser sensor has a respective base coordinate: front sensor base coordinates 1 and rear sensor base coordinates 2. The front distance 5 of the laser focusing point 3 of the front laser sensor relative to the robot end TCP and the rear distance 6 of the laser focusing point 4 of the rear laser sensor relative to the TCP can be set by the end servo controller according to the requirements of practical application, and the focusing depth and scanning range of the laser sensor can be adjusted so that the process track 7 is in the range. The front distance and the rear distance may be set or adjusted according to the actual processing environment or the requirements of the processing program, which is not particularly limited herein. The laser sensor transmits each frame of image acquired through laser imaging to the end servo controller for processing. There are two modes of image acquisition: single sampling or continuous sampling. Different sampling frequencies may also be set in the continuous sampling mode.
With continued reference to FIG. 1, the end servo controller may calculate a track compensation parameter based on data collected by the laser sensor in the end servo module and generate a control signal to the servo motor based on the track compensation parameter. As shown in fig. 1, the end servo controller mainly includes three functional modules: sensing control, track management and servo control. The sensing control module can acquire a process track point to be processed according to data acquired by the laser sensor in real time. The track management module can calculate track compensation parameters by comparing the process track points detected in real time with the pre-acquired calibration track points. The servo control module generates a control signal for the servo motor according to the track compensation parameter from the track management module so as to instruct the servo motor to execute corresponding motion to drive a corresponding control object. In this way, the process tool coupled to the servo motor may be moved along one pose to another at a specified speed to perform a corresponding process or manufacturing operation. In some embodiments, the end servo controller may further comprise a memory unit for storing relevant data and results involved in the sensing control, track management and servo control processes. The servo system with the independent sensor and the controller arranged at the tail end of the robot can provide real-time accurate track control, so that the precision of process machining can be greatly improved. And the end servo system is independent of a control system of the robot, can be adapted to a plurality of robots, and is also suitable for fixed or movable (on a rail or a conveyor belt) tools.
Referring now to FIG. 3, a diagram of a work scenario intent of a servo system for a robotic tip is shown, according to one embodiment of the present invention. The end servo module 2 in the servo system is mounted on the end joint of the robot 1 through a flange 3. The process tool 5 is coupled to a mechanical linkage 4 operated by the end servo module 2. The end servo controller (not shown) of the servo system is communicatively coupled to the end servo module 2, which may be fixed, for example, in a manner to the side of the robot end joint or to a position on the robot arm at a relatively short distance from the end servo module 2. The table 8 has a given processing path 9. The teaching path of the robot can be obtained during the robot teaching process by simple robot teaching along the process trajectory 9 in the initialization stage. Then, before starting the machining process, the robot is started to execute the process machining program corresponding to the taught path several times, during which the movement locus (position and posture) of the end servo module 2 can be tracked and measured in real time by the laser tracker 7 arranged in the scene, and thus the calibration locus of the center point of the corresponding end tool of the robot is determined based on the movement locus of the end servo module. Thus, as the robot begins the main machining process, images of the front of the robot's tip travel are acquired in real time by a laser sensor (not shown) integrated by the tip servo module 2 itself. The terminal servo controller detects a process track to be processed based on an image acquired by the laser sensor, compares the detected process track with a calibration track of a central point of a terminal tool of the robot, which is acquired in advance, to obtain corresponding compensation parameters, and generates a control signal based on the obtained compensation parameters so as to control the servo motor to perform real-time track compensation on the TCP at the terminal of the robot to meet the requirement of high-precision processing. Thus, even if the position of the process component deviates during the processing, the end servo system can enable the end TCP of the robot to accurately track the actual process track.
Also shown in fig. 3 are coordinate systems associated with the components in the scene, such as robot-based coordinates 10, end servo-based coordinates 11, TCP coordinates 12, table-based coordinates 13, and laser tracker-based coordinates 14. The laser tracker 7 may be used to measure the motion trajectory of the robot tip at the initial stage as mentioned above, and may also be used to measure the position of each coordinate system (e.g., tip servo module, process tool, robot, etc.) and the parameters associated with each other among the coordinate systems, for example, at system initialization. The laser tracker generally includes a laser head, a tracking mirror phase system, and a laser tracking controller. By means of a mirror mounted on the object, the laser tracker is able to accurately measure (or track and measure) the position and attitude of the object. The conversion may be performed between the coordinate positions measured in the above-described coordinate systems. Fig. 4 shows the respective coordinate systems involved in the above-described scene and their relationship schematic diagrams. Where o 1 denotes a table coordinate system, which may be, for example, earth coordinates, with respect to which the geometrical position of the processing component is to be determined. The laser tracker coordinate system is denoted o 6, which is fixed relative to the table coordinate system o 1. The end servo module coordinate system o 2 is a dynamic coordinate system, and changes with the motion of the robot can be obtained through measurement of a laser tracker. For example, a laser tracker mirror may be attached to the tip servo module during an initialization phase so that the motion profile of the robot tip may be measured in real time by the laser tracker. o 3 denotes the coordinate system of the robot tip TCP at the tip servo null, o 4 denotes the coordinate system of the front sensor, and o 5 denotes the coordinate system of the rear sensor, since the front sensor and rear sensor are integrated with the tip servo module, o 4 and o 5 are fixed with respect to the servo module coordinate system o 2.
Calibration of the coordinate system is usually required at the initialization of the servo system. The calibration of the coordinate systems is to determine the association parameters among the coordinate systems, and the association parameters can be expressed by a homogeneous transformation matrix. Since there are many general methods for calibrating the transformation matrix between the coordinate systems, these processes are not repeated here. In an embodiment of the present application, the transformation matrix for o 6 to o 1 is denoted by a 1, the transformation matrix for o 3 to o 2 is denoted by a 2, the transformation matrix for o 4 to o 2 is denoted by a 3, and the transformation matrix for o 5 to o 2 is denoted by a 4. Each coordinate is hereafter transformed to a geodetic coordinate representation by means of the transformation matrix described above. For example, the o 2 coordinate system is measured by a laser tracker, the measurement results of which are relative to the o 6 coordinate system, and can be transformed by a 1 to the geodetic coordinate system o 1 for representation. For another example, where the measurements of the front and rear laser sensors are relative to the sensor's coordinate system o 4,o5, respectively, the measurements may be transferred to the o 2 coordinate system and then to the relative to the earth coordinate system o 1 by a 3 and a 4, respectively. Accordingly, the TCP coordinate system o 3 may also be converted by a 2 to the o 2 coordinate system and then to the geodetic coordinate system o 1. The a 2 is calculated from the geometry of the process tool.
In describing the operation flow of the end servo system according to the embodiment of the present invention, for convenience of description, all the variables, constants, and coordinates related to each component are transformed into the same coordinate system, for example, into the earth coordinate. The end servo operation process is divided into two stages: an offline operation phase and an online operation phase. The off-line operation stage does not need to carry out the actual process, while the on-line operation stage truly carries out the actual process.
The end servo system according to some embodiments of the present invention is installed at the end joint of the robot, operates independently of the control system of the robot itself, can communicate with a laser tracker, a robot controller, etc., performs various coordinate calibration of the own system, and can store path teaching related data acquired or acquired by itself during the teaching process of the robot in a storage unit of the end servo controller. For example, during robot teaching, the end servo controller may store the acquired robot teaching path in its storage unit.
In the off-line operation stage of the end servo system, the robot is started to execute the machining program corresponding to the teaching path of the robot for several times, and each time the robot is operated under the same condition. In each running process, the running track of the measuring tail end servo module can be tracked in real time through a laser tracker arranged in an external environment. In this way, a set of position data of the end servo module measured by the laser tracker is obtained for each run. By comparing the tested multiple groups of position data, the maximum path error of the robot for executing the teaching path can be calculated. The error represents the accuracy of the repeated operation of the robot. The accuracy of the repeated operation of the robot is generally high. If the repeated operation precision obtained in this way can meet the requirements of the process, such multiple sets of test data are fitted into the calibration path or calibration track of the end servo module. Such a nominal path is expressed in the form of the position of a series of trajectory points. Hereinafter, the position of the kth track point on the calibration path of the end servo module mayAnd (c) represents a natural number. For the position of the end servo module on the calibration pathThe position of the corresponding robot end TCP can also be converted according to the size of the process tool connected with the end servo module or other component characteristics (recorded as/>) Thus obtaining the calibration track of the TCP at the tail end of the robot. In the off-line operation stage, the end servo system acquires the calibration track of the corresponding end servo module for each process track to be processed, and calculates the calibration track of the corresponding robot end TCP, namely a series of track point data/>Stored in a memory unit of the end servo controller for use in a subsequent track compensation process (described in more detail below). In the track compensation process of the online operation stage to be described below, the calibration track of the tail end servo module and/or the calibration track of the tail end TCP of the robot, which are fitted in the offline operation stage, can be used as comparison factors for real-time tracking and track compensation, so that the real-time dynamic track tracking precision of the tail end of the robot can be improved to the precision of the repeated track operation of the robot, and further, the requirements of many high-speed applications or/and high-precision applications, such as 3D printing, laser welding, spraying, gluing, high-precision compound motions (such as small circle cutting) and the like, can be met.
After the calibration track of the tail end servo module and/or the tail end TCP of the robot corresponding to each process track to be processed is obtained in the off-line operation stage, the on-line operation stage can be entered. FIG. 5 shows a schematic flow diagram of an end servo system in-line operation phase, according to one embodiment of the invention. Firstly, starting a robot program, and then capturing a target by a front sensor of the tail end servo module, wherein the target is a starting point of a process track to be processed. The pre-laser sensor continuously retrieves a machining start point of a particular part based on the geometric characteristic parameters of the start point. Once the starting target is found, the end servo controller enters tracking mode in order to get the robot end TCP to exactly the starting point. When the TCP reaches the process starting point, a process processing program can be started, and during the process, the tail end servo controller continuously tracks and detects the process track so as to control the tail end TCP of the robot to accurately track the actual process track until the process ending point is reached. The front laser sensor on the end servo module continuously detects the process track point and judges whether the process track point is a termination track point. When the TCP reaches the end point, the process is terminated and other related processes are stopped, such as turning off the sensor, stopping the trace mode. When the robot runs to the end position, the running program of the robot is terminated.
And when the robot does not find the initial target, the robot runs according to the teaching path, and the tail end servo module is in a zero position. In the actual processing process, the path of the actual process track to be processed and the track starting point and ending point are obtained by real-time detection by utilizing a front laser sensor integrated on the tail end servo module due to the uncertainty of the placement position of the workpiece. When the front sensor detects the starting point of the process track, the tail end servo controller enters a real-time tracking mode, and real-time accurate compensation is carried out on the TCP running track at the tail end of the robot so that the tail end of the robot can accurately track the corresponding process track. The process of accurately tracking a track by an end servo system according to one embodiment of the present invention is described below in conjunction with FIG. 6. As shown in fig. 6, the calibration trajectory of the robot tip TCP obtained in the off-line phase, which is already stored in the storage unit of the tip servo controller, is represented by solid circles; while the other trace, represented by a hollow dot, represents the process trace detected in real time by the front sensor on the end servo module. For ease of description of the track following process, the laser tracker and the pre-laser sensor are set to have the same sampling frequency and the control step of the servo system is set to coincide with the sampling step of the sensor, but it should be understood that this is for ease of illustration only and not by any limitation. The track following process of the end servo system can be roughly divided into four stages:
■ The first stage: the end servo module does not find the starting point of the process track, the robot runs according to the teaching path, and the end servo module is at the zero position.
■ And a second stage: when TCP arrivesThe front sensor of the end servo module finds the start point of the process trackAssume that the front sensor is relative to/>Corresponds to m sample points. By/>The corresponding calibration track point/> can be found from the storage unit of the end servo controllerFrom this, the path error can be calculatedA control signal (also referred to as a control quantity) is generated based on a single-step path error (Δt n+m/m) by using an m-step linear compensation method and is sent to a servo motor of an end servo module, so that the robot moves to a process track start point/>When it is, its position/>
■ And a third stage: at this stage, the process has started. Assuming that the current sampling timing point is k, the current position of the TCP is T k, and the control quantity applied to the end servo module is DeltaT k; the real-time detection process track point position of the current sensor is thatWhereas the previous sensor detection value/>The TCP can be accurately tracked to the following process track point through the following steps of:
1) Finding the next calibration track point from the storage unit
2) Finding the next process track point from the storage unit
3) Solving the path error of the next step
4) Solving a control increment dDeltaT k+1＝ΔTk+1-ΔTk of the next step;
5) The control end servo module applies the required control increment dΔT k+1 at a given step (distance);
6) Until TCP reaches the next process trace point,
7) Let k=k+1 repeat the above steps (1-7) until TCP reaches the end of the process trace.
■ Fourth stage: at this point the process is complete, the robot is moving along the nominal trajectory, and the end servo module is in the final control position.
In the above-described embodiments of the present invention, the end servo controller is a computing device independent of the robot controller, the process controller, the PLC controller, or the like. Different from the existing industrial robot with high repeated positioning precision and low absolute positioning precision, the absolute positioning precision of the tail end of the robot can be improved to the level of the repeated positioning precision of the robot by controlling the tail end servo module arranged at the tail end joint of the robot through the tail end servo controller, namely, the real-time dynamic track tracking precision of the robot is improved to the precision of the repeated track running of the robot, so that the requirements of high-speed or/and high-precision application are met. Moreover, since the end servo system is independent of the control system of the robot, it is applicable to any kind of robot, as well as to fixed or moving (on rails or conveyor belts) tools.
FIG. 7 shows a hardware architecture diagram of an end servo controller according to one embodiment of the invention. The end servo controller adopts a multiprocessor shared memory architecture, wherein the processor-I is mainly responsible for program control, process control, track planning and real-time path compensation algorithm. The processor-II is mainly responsible for the control of the laser sensor and image processing. The processor-III is primarily responsible for end servo control. Each processor has its own memory and can directly access the shared memory unit. The processors exchange data via the shared memory unit. The respective processors interact with external devices such as an end servo module, a laser sensor, a laser tracker, a robot controller, a process controller, a PLC controller, a notebook computer, etc. through a shared input/output interface. The end servo controller is an independent control device and is arranged near the end joint of the robot to shorten the length of a data transmission line of the three-dimensional laser sensor. The terminal servo controller integrates track management, sensing control and servo control, can synchronously process a large amount of sensor information and control terminal servo in real time under a high sampling frequency state, and therefore real-time accurate track tracking in a high-speed running process is achieved. It should be understood that the above hardware architecture is by way of example only and not by way of limitation, and that other computing devices may be employed as the end servo controller. In some embodiments, the end servo controller may communicate with an external computing device, such as a notebook computer, by wired or wireless means. The system is initially calibrated through the notebook computer, and the system can be used as a state display device in the production process, and the state of each system can be selectively observed.
In yet another embodiment of the present invention, there is further provided a computer readable storage medium having stored thereon a computer program or executable instructions which when executed implement the technical solution described in the foregoing embodiment, the implementation principle being similar and not repeated herein. In embodiments of the present invention, a computer-readable storage medium may be any tangible medium that can store data and that can be read by a computing device. Examples of a computer-readable storage medium include a hard disk drive, network Attached Storage (NAS), read-only memory, random-access memory, CD-ROMs, CD-R, CD-RWs, magnetic tapes, and other optical or non-optical data storage devices. The computer-readable storage medium may also include a computer-readable medium distributed over a network coupled computer system so that the computer program or instructions may be stored and executed in a distributed fashion.
In yet another embodiment of the present invention, there is provided an electronic device, including a processor and a memory, where the memory is configured to store executable instructions executable by the processor, where the processor is configured to execute the executable instructions stored on the memory, where the executable instructions when executed implement the technical solution described in any of the foregoing embodiments, and implementation principles are similar and are not repeated herein.
Reference in the specification to "various embodiments," "some embodiments," "one embodiment," or "an embodiment" or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases "in various embodiments," "in some embodiments," "in one embodiment," or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Thus, a particular feature, structure, or characteristic described in connection with or illustrated in one embodiment may be combined, in whole or in part, with features, structures, or characteristics of one or more other embodiments without limitation, provided that the combination is not non-logical or inoperable.
The terms "comprises," "comprising," and "having" and the like, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus. Nor does "a" or "an" exclude a plurality. Additionally, the various elements of the drawings are for illustrative purposes only and are not drawn to scale.
Although the present invention has been described by way of the above embodiments, the present invention is not limited to the embodiments described herein, but includes various changes and modifications made without departing from the scope of the invention.
Claims (8)
1. A servo system for a robot tip comprising a tip servo module coupleable to the robot tip and a tip servo controller communicatively coupled to the tip servo module, wherein:
The tail end servo module comprises a first laser sensor, a communication module, a servo motor and a mechanical linkage mechanism thereof, wherein the tail end of the mechanical linkage mechanism is connected with a process tool for processing, and the tail end servo module sends data acquired by the first laser sensor to the tail end servo controller through the communication module and receives a control signal for the servo motor from the tail end servo controller;
the servo controller is configured to: detecting a process track point to be processed according to the data acquired by the first laser sensor, calculating track compensation parameters by comparing the detected process track point with a calibration track point of a preset end tool center point of the robot, and generating a control signal for the servo motor according to the track compensation parameters to indicate that the servo motor reaches a specified position;
wherein the calibration trajectory point of the predetermined robot end tool center point is determined by the end servo controller by:
Before starting the technological processing procedure, starting the robot to execute a processing program corresponding to a teaching path of the robot for a plurality of times;
In each running process, tracking and measuring the running track of the tail end servo module in real time by a laser tracker arranged in an external environment, wherein the running track is represented by a series of position data of track points and corresponding time sequences;
And fitting the measured multiple running tracks into a calibration running track of the tail end servo module, and simultaneously calculating a calibration track point of a corresponding tail end tool center point of the robot by utilizing each track point on the calibration running track.
2. The system of claim 1, wherein the first laser sensor is disposed at a location where the tip servo module is connected to a side of a process tool and is capable of capturing an image of a forward travel of a robot tip.
3. The system of claim 1, wherein the servo controller detects a process trajectory point to be processed from the data collected by the first laser sensor and converts the corresponding process trajectory point to a robot coordinate system through a calibrated trajectory of the end servo module.
4. The system of claim 3, wherein the servo controller further comprises a memory unit for storing process trajectory points detected via the first laser sensor and for storing calibration trajectory points of a predetermined robot end tool center point.
5. The system of claim 2, wherein the end servo module further comprises a second laser sensor disposed opposite the first laser sensor on a side of the end servo module that is coupled to a process tool.
6. A control method for the servo system of any one of claims 1 to 5, comprising:
during robot processing, a first laser sensor arranged on the tail end servo module is utilized to collect images of the front of the tail end of the robot in real time and send the images to a tail end servo controller which is communicatively coupled with the tail end servo module;
detecting a process track point to be processed based on an image acquired by a first laser sensor by the end servo controller;
Comparing the detected process track point with a predetermined calibration track point of a center point of a robot end tool by the end servo controller to determine track compensation parameters, and generating a control signal for a servo motor in an end servo module according to the track compensation parameters;
the servo motor is instructed by the end servo module to reach a specified position based on a control signal from an end servo controller.
7. The method of claim 6, further comprising predetermining a nominal trajectory point for a center point of the robotic end tool by:
Before starting the technological processing procedure, starting the robot to execute a processing program corresponding to a teaching path of the robot for a plurality of times;
In each running process, tracking and measuring the running track of the terminal servo module in real time, wherein the running track is represented by position data of a series of track points;
And fitting the measured multiple running tracks into a calibration running track of the tail end servo module, and simultaneously converting each track point on the calibration running track into a calibration track point of a corresponding tail end tool center point of the robot.
8. A computer readable storage medium, characterized in that it has stored thereon a computer program, which when executed implements the method of any of claims 6-7.
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